Phonograph-reproducer



(No Model.)

T. A. EDISON. PHONOGRAPH REPBODUGER.

Patented Dec. 20, 1892.

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THOMAS A. EDISON, OF LLEWVELLYN PARK, NEW JERSEY, ASSIGNOR TO THE EDISONPI-IONOGRAPH COMPANY, OF NEW JERSEY.

PHUNOGRAPH REPRODUCER.

SPECIFICATION forming part of Letters Patent No. 488,190, dated December20, 1892.

Application filed June 7, 1888- Serial No. 276,383. (No model.)

To all whom it may concern;

Be it known that I, THOMAS A. EDISON, of Llewellyn Park, in the countyof Essex and State of New Jersey, have invented a certain new and usefulImprovement in Phonograph- Reproducers, (Case No. 774,) of which thefollowing is a specification.

The object I have in view is to improve the reproducer of my phonographso that it will be more durable, will better maintain its adjustmentunder varying conditions of heat and moisture and will more effectivelyreproduce the sound vibrations. I accomplish these ends by an improvedconstruction of the reproducing diaphragm and of the means forconnecting the reproducing point therewith. The improved diaphragm Imake of thin fabric such as silk preferably of bolting cloth. This isstretched in a frame and is then shellaced or varnished after which itis dried and is ready to be cut to the proper size for the reproducerdiaphragm, or the fabric may be stretched in the frame of the reproducerand then shellaced or varnished. The result is a diaphragm which whileexceedingly thin and flexible and well adapted to reproduce the soundvibrations, is not liable to stretch, is

impervious to moisture and is exceedingly hard and resonant. Thediaphragm, therefore, does not become Warped by changes in thetemperature and moisture of the atmos phere, and the reproducing pointmaintains the proper position relative to the phonogram blank.

For the reproducing point I use a wire of phosphor or aluminium bronze.It is secured to the frame at one side projects toward the center of thediaphragm and substantially parallel therewith, and is turned down toform the point. Instead of connecting this point with the diaghragm byan elastic strip or band of rubber I have found that a solid block ofgum rubber is better for the purpose, since there is less loss inloudness of articulation due to the elasticity of the medium between thepoint and the diaphragm. 'The wire is sprung away from the diaphragm sothat when the block of rubber is cemented both to the diaphragm and thespring wire the diaphragm will be under a slight tension.

In the accompanying drawing forming a part hereof the figure representsa sectional view of a reproducer embodying my invention, the spring wirebeing shown in dotted lines in the position it assumes before beingsecured to the solid block of gum rubber.

A is the diaphragm which is made of a fabric such as silk bolting clothwhich is stretched and then shellaced or varnished either before orafter it is secured in the frame B of the reproducer. The reproducingpoint is formed of a metal wire (J secured to the frame B at one sideand extending toward the center of the diaphragm where its end is bentdownwardly as shown. This wire is sprung away from the diaphragm asshown by the dotted lines. It is attached to the center of the diaphragmby a solid block D of gum rubber which is cemented both to the diaphragmand the wire, the wire being drawn in for the purpose so that thediaphragm will be normally held under tension.

What I claim is: I

1. The combination, in a phonograph reproducer, of a diaphragm composedof a fabric filled with a hardening material,and a reproducing pointoperatively connected thereto, substantially as set forth.

2. The combination, in a phonograph reproducer, of a diaphragm composedof a stretched fabric such as boltingcloth filled with shellac orvarnish, and a reproducing point operatively connected to saiddiaphragm, substantially as set forth.

3. In a phonograph reproducer, the combination with the diaphragm andreproducing point, of a solid block of gum rubber connecting suchdiaphragm and point, substantially as set forth.

4. In a phonograph reproducer, the combination with the diaphragm andreproducing point having a spring tension away from such diaphragm, of asolid block of gum rubber connecting such diaphragm and point,substantially as set forth. I

This specification signed and witnessed this 22d day of May, 1888.

THOS. A. EDISON. WVitnesses:

WILLIAM PELZER, A. W. KIDDLE.

